Conventionally, for example, an active energy ray curable ink that cures by an active energy ray such as ultraviolet ray and electron ray has been used for printed matters in various industrial fields.
To be specific, as the active energy ray curable ink, an active energy ray curable lithography ink containing (a) a resin, (b) an active energy ray curable compound, and (c) a pigment has been proposed in which (a) the resin is obtained by subjecting a resin acid to addition reaction with an α,β-unsaturated carboxylic acid or an anhydride thereof in an amount of 50 to 100 mol % with respect to the resin acid, and furthermore, being reacted with a polyhydric alcohol to be synthesized; (a) the resin is contained at a ratio of 10 to 40 weight % with respect to the total amount of the ink; (b) the active energy ray curable compound is contained at a ratio of 30 to 75 weight % with respect to the total amount of the ink; and (c) the pigment is contained at a ratio of 5 to 40 weight % with respect to the total amount of the ink. Also, it has been disclosed that in the active energy ray curable lithography ink, the resin acid to be used desirably contains a conjugated double bond-containing compound at a ratio of 50% or more.
To be more specific, it has been proposed that a resin is obtained by allowing a rosin to react with a maleic anhydride and then, adding a benzoic acid, a phthalic anhydride, a trimethylolpropane, and a p-toluenesulfonic acid monohydrate thereto to be subjected to dehydration condensation; a varnish is obtained by mixing the obtained resin with a dipentaerythritol hexaacrylate or the like; and furthermore, a lithography ink is obtained by using the obtained varnish (ref: Patent Document 1 (Example 1)).